LED lighting systems are becoming more and more popular. LED lighting systems may in particular be used in situations where a user wants to be able to control and change the color of a light beam provided by the LED lighting system, for example in applications as spot lighting, shop lighting, stage lighting or architectural lighting. For that purpose, a LED lighting system may be used comprising a plurality of LED diodes which generate light of different colors, such as a red LED, a green LED and a blue LED. The light of the plurality of LEDs then needs to be combined to create a single beam of the color required by the user. This combining is usually referred to as color mixing. Various methods of color mixing and devices for color mixing are known in the art. However, these known methods of color mixing may have disadvantages, such as efficiency losses, non-optimal color mixing, or a poor compatibility with other requirements, such as e.g. a control of beam direction.
LED lighting systems may also face other difficulties in design or use. For example, LED lighting systems typically require a heat sink to transfer heat away from the LED diodes during use. These requirements may especially be severe in applications where a large amount of light is required, such as stage lighting. An optimal effect of a heat sink may require operating conditions which conflict with other requirements. E.g., the dissipation of heat by convection associated with such heat sink may require forced air cooling using a fan, which may not be desirable due to e.g. the noise produced by the fan or the risk of failure of such fan. Also, it may be required to maintain the heat sink in an orientation wherein the convection is optimal, e.g. with fins, in use, remaining vertically oriented for optimal cooling capacity, which may conflict with the desire of a user to orient the LED lighting system such that the light beam is in a required direction. The user may e.g. experience that the performance of the LED lighting system will vary with beam direction.
The invention aims to provide a novel LED lighting system which preferably at least partly obviates one or more of the above-described drawbacks, and which may further preferably fulfill one or more of the above indicated desires.